Method of preparing corrosion retarding compound



Patented Sept. 5, 1933 PATENT QFHCE METHOD or PREPARING connosIoN nn'ranpma COMPOUND Orrin E. Andrus, Wauwatosa, and Milan A. Matush, Milwaukee, Wis., assignors to A. 0. Smith Corporation, Milwaukee, Wis., a corporation of New York No Drawing. Original application September 15',

1928, Serial No. 306,285. Divided and this application November 17, 1930. Serial No. 496,350

\ 11 Claims.

This invention relates to a corrosion retarding compound or material which is particularly adapted to be added to petroleum hydrocarbons or mineral oils that are actively corrosive to metals, and especially to methods of manufacturing the material.

This application is a division of our cope'nding application, Serial No. 306,285, filed September 15, 1928 entitled "Corrosive retarding compound and process of making the same.

One object of the invention is to provide a material primarily for correcting difiiculties which result from the presence ofcorrosive constituents, such as sulphur-containing compounds, free hydrogen sulphide and free mineral acids which are contained in petroleum hydrocarbons or are formed therein by heat treatment.

Another object of the invention is to provide a material which is particularly adapted to correct or retard the corrosive action of petroleum oils during storage, or when they are heat treated in such processes as distillation, coking processes, cracking, or other processes for the conversion of oils by heating.

Other objects and advantages of the material or corrosion retarding suspension which is to be added to oils will be apparent hereinafter from the more detailed description. A

Describing first the method of producing a typical batch of the material, a petroleum hydrocarbon having the characteristics of gas oil or the like is selected as a base. Any cut or fraction above the normal boiling point range of kerosene has suitable characteristics for this purpose and may be employed for the production of the material. The less viscous oils, such as gas oil have been found to be particularly useful as the products made from this oil are less viscous and more fluid, and they are easier to handle and incorporate into the oil to be treated.

To a gas oil base such as Mid-Continent gas oil or California gas oil having a gravity of approximately 30 to 32 Baum, is added an alkali such as caustic soda (NaOH). .The mixture is heated to a temperature of from 300 to 400 F. and it is agitated while it is being heated. During the heating, an oxidizing agent, such as air vis supplied to the mixture. The oxidizing material acts upon certain constituents of the hydrocarbon at these temperatures, the viscosity of the body is increased and the caustic becomes dispersed and uniformly distributed throughout the hydrocarbon in discrete form. The addition of air promotes the agitation and turbulence produced by the mechanical mixer. It is essential .condition although the particles of caustic were introduced to the base stock in a relatively coarse state. In use the batch of material thus produced by passing an oxidizing agent through a hydrocarbon in the presence of a neutralizing material, such as caustic soda is then added in a predetermined desired percentage to the oil which is to be treated. This suspension is mixed and thoroughly incorporated into the corrosive oil to offset or counteract the active corrosive constituents. The addition of the material to the oil may be efi'ected in various ways, it being essential only that the corrosion retarding compound be thoroughly dispersed throughout the mineral oil.

As suggested, the corrosion retarding com pound may be used in connection with the storage of corrosive oils, such as West Texas crude and other mineral oils which are highly corrosive to storage vessels and containers. In using the corrosion retarding compound with oils which are distilled in steam or fire stills, coking stills or other types of distillation equipment, a predetermined percentage of the material is pumped into the charging stock or it may be added directly to the still. Similar methods of incorporating the corrosion retarding compound may be used in adding the oil to cracking stills or pipe stills where oil is to be treated under relatively high pressures and temperatures. The percentage of the corrosion retarding compound to be added in each case will varyaccording to the characteristic of the oil and the type of process in which it is to be used. For example when the oil is to be stored, the amount of material to be added is varied in accordance with the percentage that is necessary for use in the oil when it is given a relatively high heat treatment.

Tests indicate that from .1% to .5% of the neutralizing ingredients by weight of the oil 105 which is to be treated is necessary for storage purposes, depending upon the corrosive activity of the oil. With oils which are to be heat treated a percentage range from .2% to 5%oi the weight of the oil may be used.

Hereinbefore caustic soda has been suggested as the only material adapted to this particular purpose. The invention however, contemplates not only the use of such a neutralizing agent, but other materials as lime, (CaO), (Ca(OH)z) soda ash, (NazCOa), and combinations of these materials, and combinations of these materials with caustic soda (NaOH). When the corrosion retarding suspension is to be used in connection with the conversion of hydrocarbons under pressure where relatively high temperatures are employed a predominance of lime in the suspension is found to give somewhat more satisfactory results. ,In such compositions suflicient caustic is used to effect a proper combination of the neutralizing materials with the mineral oil since lime alone does not readily combine with oil to form a satisfactory suspension. In addition to these materials a satisfactory corrosion retarding compound has been produced by incorporating either iron oxide (F6203) or sodium plumbite (NazPboz) into a mineral oil with or without additions of caustic soda to produce a satisfactory corrosion retarding compound. The method of incorporating these materials is substantially the same as that employed in producing a suspension of caustic soda alone. Best results in producing this addition product or suspension have been obtained when caustic soda is present during the oxidation of the hydrocarbon base.

Besides using air as an oxidizing agent in producing the corrosion retarding suspension or compound the invention contemplates the use of ozone, oxygen, peroxides and other suitable oxidizing agents.

The range of temperatures employed during the oxidation of a batch of the corrosion retarding compound is limited only within a range which will not produce objectionable or excessive oxidation and vaporization of the volatile constituents of the oil and which will give the proper or desired oxidizing efi'ect. In producing the corrosion retarding compound with gas oil and caustic soda at substantially atmospheric pressure the temperature range is commonly between 300 F. and 400 F. When the suspension or corrosion retarding mix is oxidized under pressure higher or lower temperatures may be required for different types of oils and the time required to produce a satisfactory suspension may be considerably less.

In the foregoing description, it is stated that the hydrocarbon which is used as a base for making the corrosion retarding compound shall be heated, but the heat may be supplied by adding heated oxidizing material. With some oxidizing agents very little heat is necessary to produce a satisfactory corrosion retarding suspension and difierent types of oils may require somewhat different temperatures for the preparation of the suspension.

No attempt will be made to explain the theory or character of the reaction which takes place in making the suspension. The exact theory of the reactions has not as yet been accurately ascertained except in that the actual physical characteristics have been observed in the practice of producing the material. However it has been found from these observations that a neutralizing substance such as caustic soda or combinations of the materials mentioned can be dispersed through an oil body by heating the oil and treating it with an oxidizing agent whereby a compound or suspension is produced which has a decided corrosion retarding effect when added to a corrosive mineral oil in relatively small percentages.

The corrosion retarding compound seems to have a neutralizing eflect upon free acids or corrosive sulphur-containing compounds which are contained in the oil or are produced in oils when they are subjected to heat treatment. When thoroughly mixed with an ofl the corrosion retarding compound has the property of remaining dispersed throughout the oil. Its action is uniform throughout the oil body and it has no particular tendency to concentrate, accumulate, or otherwise become local in its action.

This relatively permanent suspension would seem to depend upon the gelatinizing or coagulation of certain of the hydrocarbon constituents which tend to collect as nuclei about the discrete particles of the caustic as nuclei.

In addition to its corrosion retarding action the compound or suspension hereinbefore described may be used to sweeten certain hydrocarbon distillates by intimately combining the suspension with the distillate and then treating the mixture to remove the suspension by settling, centrifuging, filtering or distilling.

With certain cut oils which contain a considerable percentage of water in emulsified form, the suspension or compound has been used to break the emulsions and demulsify the oil water combination.

It has been found in producing the corrosion retarding suspension that caustic soda when combined with a liquid hydrocarbon and when agitated with an oxidizing agent at temperatures within the range suggested has a peculiar ailinity for certain of the oil constituents either produced or existing and the resulting product is the compound or suspension described. Other alkali substances seem to have this characteristic to less degree and this characteristic which is so noticeable in the case of caustic soda varies with different types of oil.

Many tests have been made with the corrosion retarding suspension typical of which are the following, and from these a general idea of the characteristics of the material may be obtained.

A West Texas crude oil which was highly corrosive and produced a loss of 2.0 milligrams per square centimeter of copper in 215 hours under normal storage conditions, was treated with the corrosion retarding suspension which contained caustic soda as a neutralizing agent. The mixture contained 0.2 percent of caustic soda. The loss was decreased to 1.23 milligrams per square centimeter of exposed metal. By increasing the percentage of caustic to 0.3 percent the loss was decreased to .44 milligrams, and by further increasing the percentage of caustic to 0.4 per cent the loss was practically eliminated, namely to .078 milligrams of copper per square centimeter with like periods of time elapsing in each test. Like results were obtained with soda ash and lime by utilizing a small percentage of caustic soda to produce the desired suspension.

The following tables show the results of tests which were made on Texas oils. They show the corrosive action of these oils on copper and iron at various temperatures. Various amounts of the corrosion retarding material were used. In addition, the tabulated results show the corrosive action of the oils under cracking conditions. The tests were conducted to ascertain the advantages and the effect, of the suspension when it was combined with oils under different circumstances. The selected oils are particularly difiicult to handie because or their high corrosive action on metals. In'the tabulations, the term mix refers tothe material'ior retarding corrosion which Relative corrosion in cracking still conducted under pressure of 800# per square inch and at temperatures of approximately 840" F.

Loss in milligrams per square cm Type or on Coinggaticn oi Copper Steel Vapor Va- 011 Do! 011 North central Texas gas North central Texas gas oil plus caustic soda mix. 6.3%caustic.

Plain oil 910 cm oil 100 cm mix.

Comparative tests of likecharacter were conducted for the same periods of time. Although the process has been described as a batch operation in producing the suspension or addition product, the invention contemplates the making of the compoundcontinuously.

The application of the compound to a corrosive oil will be governed by the requirements of the particular oil to overcome its corrosive action or tendencies.

The invention is hereby claimed as follows: 1. The process of producing a corrosion retarding compound which comprises the step of incorporating caustic soda in a mineral hydrocarbon oil in the form of a relatively permanent suspension by adding non-aqueous caustic soda to the hydrocarbon and blowing with air.

2.. The process of producing a corrosion retarding compound which contains caustic soda incorporated therein as a relatively permanent suspension, which comprises mixing caustic soda and a mineral hydrocarbon oil, and blowing the mixture with air at elevated temperatures.

3. The method of making a corrosion retarding compound which comprises adding a solid alkali to a mineral hydrocarbon oiland subjecting the same to an oxidizing treatment for suspending said alkali in a finely divided state of dispersion throughout the hydrocarbon.

4. The method of making a corrosion retarding compound which comprises adding a solid non-aqueous alkaline material to a mineral hydrocarbon oil, heating the mixture, and passing air, through said heated mixture to modify the mixture and cause said neutralizing material to be suspended in the hydrocarbon ina finely divided state of dispersion. 4

5. The method of making a corrosion retarding compound which comprises adding a solid non-aqueous neutralizing material to a mineral hydrocarbon oil, heating the mixture to a temperature between 300 F. and 400 F., and passing air through said heated mixture for approximately four to six hours for modifying said mixture and suspending said neutralizing material in the hydrocarbon in a finely divided state of dispersion.

6. The method of making a composition which contains alkaline material dispersed throughout" a body of oil which comprises adding alkali metal hydroxide to a mineral hydrocarbon oil, heating, and agitating in the presence of air.

'7. The method of making'a composition which contains alkaline material dispersed throughout afbody of oil which comprises adding sodium hydroxide to a mineral hydrocarbon oil, heating, and agitating in the presence of an oxidizing agent until the alkaline material is dispersed in a. finely divided state throughout the oil.

8. The method of making a composition which contains alkaline material dispersed throughout a body of oil which comprises adding an alkali metal hydroxide and an alkaline earth oxide to a mineral hydrocarbon oil, heating, and agitating in the presence of an oxidizing agent until the alkaline material is dispersed in a finely divided state throughout the oil.

9. The method of making a composition which contains alkaline material dispersed throughout a body of oil which comprises adding an alkali metal hydroxide and an alkali metal carbonate to a mineral hydrocarbon oil, heating, and agitating in the presence of a gaseous oxidizing oxygenous agent until the alkaline material is dispersed in a finely diyided state throughout the oil.

10. The method of making a material for preventing corrosion and having alkaline material dispersed throughout a body of oil, which com-- prises adding to the oil sodium hydroxide and at least one material from the group of materials (calcium oxide, calcium carbonate, sodium carbonate), heating, and agitating in the presence of an oxygenous oxidizing'agent until said alkaline materials are dispersed in a finely divided state throughout the oil.

11. The method of making a material that is readily miscible with oil for preventing corrosion of metal oil containers which comprises adding to gas oil sodium hydroxide, heating the mixture, agitating and passing air through the mixture until the lwdroxide is dispersed in finely divided state throughout the oil..

ORRIN' E. ANDRUS. MILAN A. MATUSH. 

